Simply put your relay behind the center I/P console. Constant source from the orange wire and run a wire from the Seo/Acc to get switched power for the ignition on switch. Then a wire back to the POS of the power outlet(s).
If memory serves, two are fed by one circuit and one by a separate one and then split there at the back of the Power Outlets.
You could take the fuse out of the separate one, and relay it there under the hood.
Being sure to put an inline fuse.